net: ipmr: add mfc newroute/delroute netlink support

This patch adds support to add and remove MFC entries. It uses the
same attributes like the already present dump support in order to be
consistent. There's one new entry - RTA_PREFSRC, it's used to denote an
MFC_PROXY entry (see MRT_ADD_MFC vs MRT_ADD_MFC_PROXY).
The already existing infrastructure is used to create and delete the
entries, the netlink message gets converted internally to a struct mfcctl
which is used with ipmr_mfc_add/delete.
The other used attributes are:
RTA_IIF - used for mfcc_parent (when adding it's required to be valid)
RTA_SRC - used for mfcc_origin
RTA_DST - used for mfcc_mcastgrp
RTA_TABLE - the MRT table id
RTA_MULTIPATH - the "oifs" ttl array

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ipmr.c

@@ -66,6 +66,7 @@
 #include <net/netlink.h>
 #include <net/fib_rules.h>
 #include <linux/netconf.h>
+#include <net/nexthop.h>
 
 struct ipmr_rule {
 	struct fib_rule		common;
@@ -2339,6 +2340,130 @@ done:
 	return skb->len;
 }
 
+static const struct nla_policy rtm_ipmr_policy[RTA_MAX + 1] = {
+	[RTA_SRC]	= { .type = NLA_U32 },
+	[RTA_DST]	= { .type = NLA_U32 },
+	[RTA_IIF]	= { .type = NLA_U32 },
+	[RTA_TABLE]	= { .type = NLA_U32 },
+	[RTA_MULTIPATH]	= { .len = sizeof(struct rtnexthop) },
+};
+
+static bool ipmr_rtm_validate_proto(unsigned char rtm_protocol)
+{
+	switch (rtm_protocol) {
+	case RTPROT_STATIC:
+	case RTPROT_MROUTED:
+		return true;
+	}
+	return false;
+}
+
+static int ipmr_nla_get_ttls(const struct nlattr *nla, struct mfcctl *mfcc)
+{
+	struct rtnexthop *rtnh = nla_data(nla);
+	int remaining = nla_len(nla), vifi = 0;
+
+	while (rtnh_ok(rtnh, remaining)) {
+		mfcc->mfcc_ttls[vifi] = rtnh->rtnh_hops;
+		if (++vifi == MAXVIFS)
+			break;
+		rtnh = rtnh_next(rtnh, &remaining);
+	}
+
+	return remaining > 0 ? -EINVAL : vifi;
+}
+
+/* returns < 0 on error, 0 for ADD_MFC and 1 for ADD_MFC_PROXY */
+static int rtm_to_ipmr_mfcc(struct net *net, struct nlmsghdr *nlh,
+			    struct mfcctl *mfcc, int *mrtsock,
+			    struct mr_table **mrtret)
+{
+	struct net_device *dev = NULL;
+	u32 tblid = RT_TABLE_DEFAULT;
+	struct mr_table *mrt;
+	struct nlattr *attr;
+	struct rtmsg *rtm;
+	int ret, rem;
+
+	ret = nlmsg_validate(nlh, sizeof(*rtm), RTA_MAX, rtm_ipmr_policy);
+	if (ret < 0)
+		goto out;
+	rtm = nlmsg_data(nlh);
+
+	ret = -EINVAL;
+	if (rtm->rtm_family != RTNL_FAMILY_IPMR || rtm->rtm_dst_len != 32 ||
+	    rtm->rtm_type != RTN_MULTICAST ||
+	    rtm->rtm_scope != RT_SCOPE_UNIVERSE ||
+	    !ipmr_rtm_validate_proto(rtm->rtm_protocol))
+		goto out;
+
+	memset(mfcc, 0, sizeof(*mfcc));
+	mfcc->mfcc_parent = -1;
+	ret = 0;
+	nlmsg_for_each_attr(attr, nlh, sizeof(struct rtmsg), rem) {
+		switch (nla_type(attr)) {
+		case RTA_SRC:
+			mfcc->mfcc_origin.s_addr = nla_get_be32(attr);
+			break;
+		case RTA_DST:
+			mfcc->mfcc_mcastgrp.s_addr = nla_get_be32(attr);
+			break;
+		case RTA_IIF:
+			dev = __dev_get_by_index(net, nla_get_u32(attr));
+			if (!dev) {
+				ret = -ENODEV;
+				goto out;
+			}
+			break;
+		case RTA_MULTIPATH:
+			if (ipmr_nla_get_ttls(attr, mfcc) < 0) {
+				ret = -EINVAL;
+				goto out;
+			}
+			break;
+		case RTA_PREFSRC:
+			ret = 1;
+			break;
+		case RTA_TABLE:
+			tblid = nla_get_u32(attr);
+			break;
+		}
+	}
+	mrt = ipmr_get_table(net, tblid);
+	if (!mrt) {
+		ret = -ENOENT;
+		goto out;
+	}
+	*mrtret = mrt;
+	*mrtsock = rtm->rtm_protocol == RTPROT_MROUTED ? 1 : 0;
+	if (dev)
+		mfcc->mfcc_parent = ipmr_find_vif(mrt, dev);
+
+out:
+	return ret;
+}
+
+/* takes care of both newroute and delroute */
+static int ipmr_rtm_route(struct sk_buff *skb, struct nlmsghdr *nlh)
+{
+	struct net *net = sock_net(skb->sk);
+	int ret, mrtsock, parent;
+	struct mr_table *tbl;
+	struct mfcctl mfcc;
+
+	mrtsock = 0;
+	tbl = NULL;
+	ret = rtm_to_ipmr_mfcc(net, nlh, &mfcc, &mrtsock, &tbl);
+	if (ret < 0)
+		return ret;
+
+	parent = ret ? mfcc.mfcc_parent : -1;
+	if (nlh->nlmsg_type == RTM_NEWROUTE)
+		return ipmr_mfc_add(net, tbl, &mfcc, mrtsock, parent);
+	else
+		return ipmr_mfc_delete(tbl, &mfcc, parent);
+}
+
 #ifdef CONFIG_PROC_FS
 /* The /proc interfaces to multicast routing :
  * /proc/net/ip_mr_cache & /proc/net/ip_mr_vif
@@ -2692,6 +2817,10 @@ int __init ip_mr_init(void)
 #endif
 	rtnl_register(RTNL_FAMILY_IPMR, RTM_GETROUTE,
 		      NULL, ipmr_rtm_dumproute, NULL);
+	rtnl_register(RTNL_FAMILY_IPMR, RTM_NEWROUTE,
+		      ipmr_rtm_route, NULL, NULL);
+	rtnl_register(RTNL_FAMILY_IPMR, RTM_DELROUTE,
+		      ipmr_rtm_route, NULL, NULL);
 	return 0;
 
 #ifdef CONFIG_IP_PIMSM_V2